Study On Gas-Solid Two Phase Flow And Heat Transfer In Fluidized Bed Coal Gasifier

Coal gasification technology is widely used in chemical products manufacturing industry.the numerical simulation method.The gasification process of the fluidized bed coal gasifier is analyzed comprehensively by simulation method,which is helpful for improving the gas combustion components,the gas calorific value and carbon conversion rate in the actual production.In this paper,took the fluidized bed coal gasifier as the research object,physical model and mathematical model were established.The turbulent model was based on the realizable k-? two-equation model.The P-1 model was used for the heat transfer.The non-premixed combustion model was used for gasification and combustion of pulverized coal particles.The gas phase motion was simulated by Euler method.The pulverized coal particles were regarded as discrete phase and was simulated by Discrete Phase Model model.Accomplished the numerical simulation of fluidized bed coal gasifier gasification process by FLUENT.The conditions of gas phase temperature,speed and component of coal gasifier was simulated.The influence of different operating parameters(gasifier mass flow,pulverized coal preheating temperature,pulverized coal particle size and coal injection speed)on the gasification process and the results were studied based on the reference conditions.The main conclusions of this paper are as follows:When the gasifier(oxygen and water vapor)is injected from the nozzle,the initial temperature and the initial velocity are 485 K and 39.4m / s.After the pulverized coal particles and the gasifier are mixed with the high temperature gas in the reactor,pyrolysis,gasification,combustion and other reactions are conducted.The final coal gas temperature is 1190 K,and the flame diameter is 400-500 mm.After the gasifier is mixed with low-speed gas in the reactor and transmit momentum,air velocity along the horizontal and vertical are gradually reduced,the final coal gas speed is 2.07 m / s;chemical reactions mainly conduct in the high temperature reaction zone,mainly generate CO,H2 and CO2,consume O2 and water vapor.When the gasfier mass flow increases,the optimization of coal gasification result has a greatest value;the higher the pulverized coal preheating temperature is,and the smaller the pulverized coal particle size is,the better the result of coal gasification is.The coal injection speed has little influence on coal gasification result.According to the results,the optimum operating parameters of coal gasification are the gasfier mass flow of 7.2kg/s(gas ratio of 1.29),the pulverized coal preheating temperature of 505 K,the pulverized coal particle size of 30?m and the coal injection speed of 6.8m/s in the range of research.